Honestly I'm shocked that my phone could disallow me tethering just because some third-party operator told him so, without any technical reasons. I paid my money to Apple, they got their salary from my money, yet they don't respect my freedom. The same with recording the calls. It's an extremely basic feature which is present in almost any Android phone AFAIK. That's what I don't like about iPhones, they have no respect for their owner. It's like a car with built-in limiter to 140 KM/h just because there are no roads where I can drive faster. It's my business, my liability.